In my experience students will have the most positive experience when they are working on something that they are genuinely interested in and which is not too repetitive. I therefore discuss with the student which part of the project they are most interested in, and I try not to have the student do the same task over and over again for long periods of time. Though weekly meetings with my students, that allow them to ask questions, I aim to evaluate their progress. I am personable and try to answer my student's emails within the same day. I always discuss the opportunity for the student to get something more concrete out of their work than just the experience. This could be for example a poster presentation at the undergraduate research symposium, or something else that they can put on their resume.